PHYSIOLOGY. ' 



723 



is fundamentally different from that of the or- 

 dinary digestive enzymes, the subject has been 

 more fully investigated by A. Sheridan Lea and 

 W. Lee Dickinson. Their conclusions are ad- 

 verse to the validity of Fick's view, and in the 

 results they obtained they see nothing but a con- 

 firmation of what had previously been believed 

 as to the mode of action of rennin and fibrin 

 ferment being essentially similar, as far as con- 

 cerns contact between the ferment and the altera- 

 ble substance to that of other well-characterized 

 enzymes. 



The object of a series of plethysmographic 

 studies by Henry Sewall and Elmer'Sanford was 

 to determine the effect of electrical stimulation 

 upon the blood vessels of man by measuring the 

 changes in volume of the organ supplied by them. 

 The organs stimulated were the finger, by pas- 

 sage of electric currents superficially through it,, 

 and those tissues of the forearm to which the ul- 

 nar nerve is distributed below the elbow. Differ- 

 ent forms of current were applied, of which rate 

 of interruption and direction appeared to have, of 

 themselves, no characteristic influence. The in- 

 tensity of the stimulus, on the other hand, was 

 of the greatest importance in determining the 

 effects produced. Strong stimulation caused pro- 

 nounced and long-continued contraction of the 

 blood vessels, while weak or moderately strong 

 stimulation was accompanied, after an initial 

 temporary contraction, by vascular dilatation. 

 The nature and extent of the after-action ap- 

 peared to depend more on the condition of irri- 

 tability of the vaso-motor mechanism than on the 

 strength or character of the irritation employed. 

 The results obtained from direct stimulation of 

 the finger differed from those due to irritation of 

 the ulnar nerve in the greater frequency with 

 which simple contraction occurred in the first 

 case, while in the second case dilatation both 

 during and after stimulation was a usual effect. 

 The most important conclusion to which the ex- 

 periments lead is that the results appear to be 

 due not to direct excitement of the peripheral 

 blood vessels or their motor nerves, but to reflex 

 action through stimulation of sensory filaments. 



It has been observed that intraperitoneal trans- 

 fusion of blood is followed in a very short time by 

 an increase in the number of corpuscles, amount- 

 ing sometimes to 34 or 40 per cent, in the course 

 of a few hours. The effect was ascribed by some 

 authors to absorption of red corpuscles from the 

 peritoneal cavity ; but William Hunter main- 

 tained that the rise in number was more appar- 

 ent than real, and was due to an increase in the 

 density of the circulating blood resulting from 

 the operation. The operation was accompanied 

 by a considerable amount of irritation as well as 

 by changes in the blood, and indicated to Mr. 

 Hunter that both results pointed to an effusion 

 of serum from the vessels of the peritoneal serous 

 surfaces. This effusion, leading to a concentra- 

 tion of the circulating blood, would, apart from 

 any absorption of corpuscles, cause an apparent 

 rise in the number of corpuscles per cubic mille- 

 metre of blood remaining. Besides a rapid in- 

 crease in density, which subsided as rapidly, a 

 more gradual and more permanent increase was 

 observed, which was regarded as due to an ex- 

 cess of corpuscles. The author's later experi- 

 ments confirm the correctness of his explanation. 



Apart from their bearing on the fate of corpus- 

 cles after transfusion, his results point to peri- 

 toneal transfusion as an effective method for 

 raising the specific gravity of the blood. 



It was established by Haycraft that a watery 

 extract of the anterior part of the medicinal 

 leech has, when mixed with shed blood or in- 

 jected into the circulation, a strong delaying or 

 preventing action upon clothing. W. L*. Dick- 

 inson has experimented with a view to isolating 

 the active principle of this extract and studying 

 its action. The reactions of leech extract show 

 that it contains a proteid with some features in 

 common with Kiihne's proto-albumen, and other 

 features in common witn deutero-albumen. It is 

 found to exercise a destructive action on fibrin 

 ferment ', and there seems to be ground for con- 

 cluding that cell globulin may be deprived by 

 it of fibrino-plastic power without suffering alter- 

 ation in its physico-chemical qualities. 



An instrument used by Dr. Gr. N. Stewart to 

 measure differences of temperature between the 

 artery and vein of a limb or organ, consists of a 

 pair of vulcanite holders, each having a fine plati- 

 num wire disposed in a groove which receives the 

 vessel. The measurement is made by the resist- 

 ance method. The method has the advantage 

 that the vessels do not require to be opened. 

 The temperature measured is really that of the 

 outside of the vessel, but when the latter is in- 

 closed in the groove this can not differ apprecia- 

 bly from that of the blood. 



Concerning the effects of inhalations of certain 

 anaesthetics on the circulation and respiration, 

 Dr. Lohers says that bromethyl slows the respira- 

 tion, leaving the inspirations unaltered, but ren- 

 dering the expirations weaker and weaker till 

 they disappear; at an early stage of its action 

 respiration becomes again normal if the animal 

 is supplied with fresh air, but later on this 

 is not the case, and death ensues by the ac- 

 tion of the drug on the heart. The effect on the 

 circulation is to quicken it at once ; the blood 

 pressure falls, the pulse becomes arhythmic, and 

 finally ceases ; the left side of the heart is now 

 found to be empty, while the right is gorged with 

 blood. It hence appears that bromethyl affects 

 the two halves of the heart differently, and thus 

 probably gives rise to asymmetry of the pulse. 

 When the vagi are cut off the effect of the drug 

 on both circulation and respiration is longer in 

 appearing. Nitrous oxide has a more powerful 

 action on respiration ; the inspirations diminish 

 rapidly and cease suddenly. Normal respiration 

 may be restored by fresh air if the action of the 

 drug has not been too prolonged. The effect on 

 the heart is to increase the blood pressure. The 

 general conclusion is that bromethyl must be 

 more cautiously employed than nitrous oxide. 



Respiration. The object of a paper by 

 Henry Sewall and Myra E. Pollard on the rela- 

 tions of diaphragmatic and costal respiration is 

 to emphasize the physiological relations already 

 known to exist between the different groups of 

 respiratory muscles (those which produce changes 

 in the capacity of the thorax by direct movement 

 of its bony framework and the diaphragm and 

 muscles of the abdominal wall). The results of 

 experiments directed to that point show that the 

 vital capacity as determined by costal is much in 

 excess of that detormined by diaphragmatic res- 



